not sure what your meaning by the seal turning.Is it the seal thats actually turning inside the end cap of the cylinder or is the end cap on the cylinder turning on the cylinder.Its a possibility that the end cap has come loose.Your going to have to make sure the end cap is tight that threads onto each end of the cylinder.That means your going to have to remove the mounting bracket and see if you can tighten up the end cap,on the cylinder.Let me know what you find,thanks Larry